Modern metal rolling mills advance a metal strip on a pass line between working rolls at speeds up to 6000 feet per minute. To efficiently cool the rolls of such high speed mills, sophisticated liquid coolant systems are employed to direct coolant sprays in adequate amounts onto the working rolls. U.S. Pat. No. 4,247,047 issued Jan. 27, 1981 for a MODULAR ZONED DIGITAL COOLANT CONTROL SYSTEM FOR STRIP MILL ROLLS reflects the latest technology for this purpose. In the patent, banks of digitally controlled coolant nozzles contained in common coolant header valve modules are selectively turned off or turned on in zones to supply with precision the amounts of liquid coolant necessary to maintain the proper condition of the metal strip passing at high speed through the mill rolls.
The diverse usage of the rolled metal strip in today's manufacturing processes has created a new problem which heretofore has not been dealt with in any orderly and satisfactory manner. This problem is the permanent staining of the metal strip by the coolant liquid in the mill to such an extent that the strip is unacceptable to product manufacturers and end users. This staining is caused by allowing liquid coolant to remain on one or both surfaces of the strip after the strip passes through the working rolls and is coiled by a conventional coiler.
Accordingly, the objective of the present invention is to deal successfully with this problem of the industry through provision of a pneumatic system employed in concert with a liquid coolant distribution system to effectively clean or remove substantially all coolant from the metal strip near its exit from the working rolls and before the strip reaches the coiler.
More particularly, it is the objective of the invention to provide a coolant removing apparatus and method in which about 80% of the liquid coolant is removed at the upstream sides of the working rolls through the action of pressurized air jets which prevent the passage of liquid coolant through the gaps between the working rolls outwardly of the longitudinal edges of the metal strip, followed by the removal of substantially all remaining coolant near the downstream sides of the rolls by the combined action of positive pressure air jets on opposite sides of the strip to dislodge the coolant so as to render it airborne and the simultaneous action of an aspirator system to pull the airborne droplets away from the strip and deliver them to a remote reclaiming or recycling point where the valuable liquid can be recovered and reused. This aspirating operation prevents polluting of the atmosphere in the vicinity of the working rolls and liquid coolant apparatus.
Still another object of the invention is to provide a pneumatic liquid coolant removal system which can form an integral part of the digital coolant control system in U.S. Pat. No. 4,247,047, thus constituting an important improvement on that patent.
A further object is to provide an efficient and economical coolant removal system for a strip rolling mill which is rugged and durable, compact and easy to maintain.
Other features and advantages of the invention will become apparent during the course of the following detailed description.